Scientific Name: Scullcap
Other Names: American Scullcap, Blue Pimpernel, Common Scullcap, Helmet Flower, Hoodwort, Mad-Dog Weed, Quaker Bonnet, Scutellaria lateriflora, Skullcap

Who is this for?

Uses

Note: American scullcap (Scutellaria lateriflora) is different from a related plant called Baikal or Chinese scullcap (Scutellaria baicalensis), which may be used to treat infections and cancer. In addition, American scullcap sometimes has been found to be contaminated with similar plants, such as germander, that are more likely to cause serious side effects.

At one time, American scullcap was used widely as a weak sedative. It was included in tonics to treat anxiety, insomnia, and nervousness. It was also thought to relieve muscle cramps, so it was often included in preparations for menstrual cramps and other “female complaints”. However, very little scientific evidence exists to support any medical properties for American scullcap, and its use has diminished greatly over the last several decades, as medications that are more effective have been developed. A very small recent study of healthy adults does seem to show that American scullcap has some calming effects, but the results of that study are questionable. While American scullcap may still be taken to relieve anxiety and produce sleepiness, other herbals, non-prescription drugs, and prescription products have been proven to produce better results with less chance of side effects.

Cases of liver damage, including some that resulted in death, have occurred in individuals who were taking American scullcap. Although the liver damage was likely to have been caused by another substance contaminating the American scullcap, individuals who have any liver conditions and those who drink large amounts of alcohol should not take American scullcap. Liver damage can take years to develop and it may not have obvious signs. Tests of liver function may be needed to diagnose it. A doctor should be notified immediately if any of the following symptoms occur while American scullcap is being taken:

• Excessive fatigue
• Extreme widespread itchiness
• Nausea, vomiting or diarrhea
• Pain or swelling in the upper right part of the abdomen
• Yellowing of the skin or the white parts of the eyes

Precautions

Not enough is known about how American scullcap might affect developing babies, infants, or children to recommend its use by pregnant or breast-feeding women or children under the age of 18.

What side effects should I watch for?

Major Side Effects

Reportedly, exceptionally large doses of American scullcap tincture have resulted in seizure-like movements of the arms and legs. A tincture is a relatively weak liquid preparation made by soaking plant parts in a solvent such as alcohol and then straining out the solid particles, leaving the active chemicals in the solution. Due to the decreasing use of American scullcap since about 1950, most reports of side effects involve case reports from the early 1900's, when records frequently were not as complete or accurate as later reports. No large, well-controlled studies of American scullcap have been carried out in humans to prove or disprove either its effectiveness or its potential for side effects. If American scullcap is used, doses should be limited to no more than is recommended on the package. Usually, American scullcap is taken for only a few days at a time.

Less Severe Side Effects

Although recommended doses of American scullcap are not thought to result in side effects, one case of confusion and irregular pulse from an exceptionally large dose has been reported in medical literature.

What interactions should I watch for?

Prescription Drugs

No interactions have been reported between American scullcap and prescription drugs. However, because American scullcap may promote sleepiness, it may intensify the effects of drugs that also cause drowsiness. The effects of the drug may be exaggerated, resulting in sedation or mental impairment. Prescription drugs that can cause sleepiness include:

• Anticonvulsants such as carbamazepine, phenytoin, and valproic acid
• Barbiturates such as phenobarbital
• Benzodiazepines such as alprazolam and diazepam
• Drugs for insomnia such as Lunesta, Rozerem, Sonata, and zolpidem
• Tricyclic antidepressants such as amitriptyline, amoxapine, doxepin, and nortriptyline

Non-prescription Drugs

Although no interactions have been reported between American scullcap and non-prescription drugs, the sleep-producing effects of over-the-counter (OTC) products containing diphenhydramine or doxylamine may be enhanced by taking American scullcap at the same time. Diphenhydramine doxylamine are contained in many OTC sleep aids as well as in some cough and cold products. Therefore, taking medications containing diphenhydramine or doxylamine with American scullcap may result in excessive drowsiness.

Herbal Products

• Catnip
• Hops
• Kava
• St. John's Wort
• Valerian

Foods

No interactions between American scullcap and foods have been reported, but drinking alcohol at the same time as using American scullcap may result in increased drowsiness.

Some interactions between herbal products and medications can be more severe than others. The best way for you to avoid harmful interactions is to tell your doctor and/or pharmacist what medications you are currently taking, including any over-the-counter products, vitamins, and herbals. For specific information on how American scullcap interacts with drugs, other herbals, and foods and the severity of those interactions, please use our Drug Interactions Checker to check for possible interactions.

Should I take it?

American scullcap is different from a related species called Baikal scullcap or Chinese scullcap (Scutellaria baicalensis). While the roots of Baikal scullcap have been used in Asian countries to fight infections, it is the “aerial parts"—flowers, leaves, and stems—of American scullcap that are collected and dried for medical use. A perennial that can be up to three feet tall, American scullcap is a member of the mint family of plants. Growing wild in woods and damp meadows throughout North America, it bears clusters of distinctive cap or helmet-shaped blue or purple flowers in late summer.

In colonial times, American scullcap was believed to be effective for treating rabies, but that use has been disproved. At various times, it has also been advocated as a tonic for alleviating premenstrual syndrome, a remedy for epilepsy, treatment for mental illnesses, and a fever reducer. None of these uses has been proved in clinical studies. However, because it has slightly calming effects, American scullcap has been used to relieve nervous tension and help bring on sleep. Today, more effective and less potentially harmful remedies are available.

Dosage and Administration

Note: American scullcap products may be contaminated with other substances, such as germander, a similar-looking plant that is sometimes called pink scullcap. Taking germander has caused liver damage and death. Individuals who decide to use American scullcap should be sure to purchase a reputable commercial product.

Although dosing for American scullcap varies, a common recommendation for its use is 1,000 mg to 2,000 mg (one gram to 2 grams) of the dried herb made into a tea by soaking it in about 5 ounces of boiling water for 5 minutes to 10 minutes. Solid particles are removed before the tea is ingested. American scullcap tea may be taken up to three times a day. Although American scullcap may be available by itself, more often it is combined with valerian or other herbals to increase their sedating effects.

Summary

In current western herbal medicine, the main use of American scullcap is for mild sedation—usually in combination with other sedating herbals.

Risks

Taking American scullcap has been associated with several cases of liver damage. Although the damage likely was caused by a similar plant called germander, individuals with any type of liver condition should not take American scullcap. Pregnant women, women who are breast-feeding, and children under the age of 18 should also avoid taking American scullcap.

Side Effects

American scullcap may be contaminated with germander, a similar-looking plant, which has been found to damage the liver. Very large doses of American scullcap have been reported to cause confusion, irregular pulse, or movements that mimic seizures.

Interactions

Interactions with American scullcap are not well defined. Because it promotes sleepiness, American scullcap can increase the sedation associated with certain prescription drugs, non-prescription drugs, other herbals, and alcohol. It should not be taken at the same time as drugs for anxiety, colds and coughs, epilepsy, or insomnia. Many other medications may cause drowsiness, so a doctor or pharmacist should be consulted before American scullcap is taken with any prescription, non-prescription, or herbal product.

Last Revised July 18, 2007

References

Anon: Scullcap. In: DerMarderosian A, Beutler JA, eds. Facts and Comparisons: The Review of Natural Products. St. Louis, MO, Facts and Comparisons. January 1993.

Awad R, Arnason JT, Trudeau V, et al. Phytochemical and biological analysis of skullcap (Scutellaria lateriflora L.): a medicinal plant with anxiolytic properties. Phytomedicine. 2003;10(8):640-649.

Castot A, Djezzar S, Deleau N, Guillot B, Efthymiou ML. Pharmacovigilance off the beaten track: herbal surveillance or pharmacovigilance of medicinal plants. [article in French]. Therapie 1997;52(2):97-103.

Cauffield JS, Forbes HJ. Dietary supplements used in the treatment of depression, anxiety, and sleep disorders. Lippincotts Primary Care Practice. 1999;3(3):290-304.

Haughton C. Scutellaria lateriflora (L). Revised September 23, 2002. Available at: http://www.purplesage.org.uk/profiles/skullcap.htm. Accessed March 28, 2003.

HealthNotes, Inc. American scullcap. 2002. Available at: http://www.mycustompak.com/healthNotes/Herb/Scullcap_American.htm Accessed March 28, 2003.

Jellin JM, Gregory P, Batz F, Hitchens K, et al, eds. Pharmacist's Letter/Prescriber's Letter. Natural Medicines Comprehensive Database, 3rd Edition. Stockton CA: Therapeutic Research Facility, 2000.

Larrey D, Vial T, Pauwels A, et al. Hepatitis after germander (Teucrium chamaedrys) administration: another instance of herbal medicine hepatotoxicity. Annals of Internal Medicine. 1992;117(2):129-132.

McGuffin M, Hobbs C, Upton R, Goldberg A, eds. American Herbal Product Association’s Botanical Safety Handbook. Boca Raton, FL: CRC Press; 1997.

Natural Medicines Comprehensive Database, Online Edition. Pharmacist's Letter/Prescriber's Letter. Stockton CA: Therapeutic Research Facility, 2006. Available at: http://www.pharmacistsletter.com/(S(ulqz3s45omt3ag55um4kj345))/home.aspx?li=1&st=1&cs=&s=ND.

Peirce A. The American Pharmaceutical Association Practical Guide to Natural Medicines. New York: Stonesong Press; 1999.

Sarris J. Herbal medicines in the treatment of psychiatric disorders: a systematic review. Phytotherapy Research. 2007;21(8):703-716.

Webb G. Sorting out scullcap. HerbalClip. November 5, 1997. Available at: http://www.herbalgram.org/wholefoodsmarket/herbclip/review.asp?i=41987 Accessed April 25, 2003.

Wohlmuth H. Skullcap (Scutellaria lateriflora). No date given. Available at: http://www.botanicalpathways.com/issue13/skullcap.htm Accessed April 17, 2003.

Wolfson P, Hoffmann DL. An investigation into the efficacy of Scutellaria lateriflora in healthy volunteers. Alternative Therapy in Health and Medicine. 2003;9(2):74-78.

Last Revised July 18, 2007

Note: The above information is not intended to replace the advice of your physician, pharmacist, or other healthcare professional. It is not meant to indicate that the use of the product is safe, appropriate, or effective for you.

In general, herbal products are not subject to review or approval by the U.S. Food and Drug Administration (FDA). They are not required to be standardized, meaning that the amounts of active ingredients or contaminants they contain may vary between brands or between different batches of the same brand. Not all of the risks, side effects, or interactions associated with the use of herbal products are known because few reliable studies of their use in humans have been done.

This information is provided for your education only. Please share this information with your healthcare provider and be sure that you talk to your doctor and pharmacist about all the prescription and non-prescription medicines you take before you begin to use any herbal product.

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